1. Field of the Invention
The present invention relates to an optical member such as a lens element preferably applicable to an optical communication devices, tools, and systems and more particularly, to an optical member such as a micro-lens suitable for constituting things by mean of a microscopic optical element of the diffraction type such as a Computer Generated Holographic (CGH) optical element. The invention also relates to a method for manufacturing the optical member as described above, an optical module, and a method for mounting the optical member as mentioned above.
2. Prior Art
With regard to the optical member coupled to a laser diode and an optical fiber in the field of the optical communication, the Japanese patent publication No. 7-199006 and the ditto No. 11-295561 have already disclosed it publicly. The former proposes an optical coupling by means of a ball lens in the form of a sphere while the latter describes a circular lens provided with an annular portion formed along the external edge of the lens.
There has been also devised and reported an optical member like a lens which are manufactured by using the photo-lithography and etching technique and used in the above field. In this example, a lens or the like having a desired shape is formed on the silicon substrate by using the photolithographic process.
Being formed in this way, the lenses are often treated in the thin film formation process to be coated with a tin film, an anti-reflection film, a filtration film and so forth, for instance.
These lenses are arranged and mounted in their respective predetermined positions on a semiconductor substrate, on which a laser diode, an optical fiber, and other elements are mounted, such that the respective optical axes of them meets those of corresponding elements. At the time of mounting, these lenses are arranged on the corresponding grooves formed on the semiconductor substrate, thereby being appropriately positioned to be coupled to the laser diode, the optical fiber and other corresponding elements.
However, the diameter of the conventional micro-lens like the ball lens or the lens provided with the annular portion as describe above, is no more than 100 xcexcm through 200 xcexcm. Consequently, it would never be easy to handle and correctly arrange such a minute micro-lens in a predetermined position.
Then, even if trying to handle and hold the minute micro-lens by making use of the negative pressure, the micro-lens provided with the annular portion has a circular curved surface along the circumference thereof, so that it would not properly work to suck in and hold such lens by utilizing the negative pressure from the side portion of the lens.
Similarly, in case of the lens as produced in the above process utilizing the photolithographic etching, the lens size becomes also very small. In this manufacturing process, a lot of lens elements are formed in usual on a single silicon substrate, and at the stage where the lens element formation is completed, lens elements are split into a lot of individual lens elements. Consequently, it would become so difficult to collect and handle them one by one.
Furthermore, in the thin film formation process for forming an anti-reflection film and so on, a large number of individual lenses have to be drawn up in a predetermined form such that their respective surfaces to be coated with the thin film are kept at a same level, and then, to be moved to the vapor deposition process. This is also neither easy nor efficient.
Similarly, in case of the process of mounting the individual lens elements, it would also be not easy to handle and arrange such minute lens elements in the corresponding predetermined positions, respectively.
Heretofore, when mounting the lens element like this on the supporting substrate, there has been often taken such a way that the positioning of each element is carried out by using the upper side of the lens formation plane as a reference point, and the mounting is then executed by bringing the side face of the lens formation plane into contact with the supporting substrate. However, this way sometimes causes a mounting error depending on the external form of the lens element. For instance, if the angle made by the lens formation plane and the said face thereof includes a certain error, there is caused a distance error related to the slant of the lens element. This distance error becomes a significant cause which reduces the efficiency of the optical coupling between the lens element and the laser diode, optical fiber, and so forth.
Then, the invention has been made for obviating such problems as described above. Accordingly, it is an object of the invention to provide an optical member which can be handled with ease, a method for manufacturing the same, and an optical module including the same. Furthermore, another object of the invention is to provide an optical member which can be sucked in and held with ease by utilizing negative pressure. Still further, another object of the invention is to provide an optical member which can be mounted with high accuracy and ease, a method for mounting the same, and an optical module packaged with high accuracy and ease.
In order to solve problems as described above, according to the invention, there is provided an optical member including a luminous flux conversion portion formed on the surface of an optical substrate; an edge portion formed along a part of the circumference of the luminous flux conversion portion; and a handling portion which is provided on the side of the other part of the circumference of the luminous flux conversion portion in a plane approximately in parallel with the surface of the luminous flux conversion portion, and is extended with a width wider than the luminous flux portion.
In the above optical member as described above, the optical member includes an optical element, an optical element aggregation, an optical element aggregation group and so forth; to put it more concrete, a lens element, a lens element aggregation, a lens element aggregation group, lens array and so forth.
In the above optical member as described above, this specification and scope of claims for patent as attached thereto, the luminous conversion portion means those which have the function of converting the luminous flux, for instance, the function of converging, diverging, reflecting, deflecting the luminous flux or the like. Also, depending on the arrangement condition of it, the luminous conversion portion includes those which convert the incident luminous flux into parallel light rays, or divide the incident luminous flux into a plurality of component waves. The lens, diffraction optical element, and forth are concrete examples of the luminous flux conversion portion.
The optical substrate may be formed by means of a crystalline substrate such as a silicon crystal substrate. Besides, the crystalline. substrate may be formed by using other materials than silicon, for instance, GaAs, InP, GaP, SiC, Ge and so forth.
According to the constitution of the optical member as described above, the handling portion can be held by means of a griping means or a suction means utilizing the negative pressure. With this, when handling the optical member, it becomes possible to hold the optical member by the handling portion thereof. Comparing with the prior art, therefore, the optical member can be much easily handled neither giving any damage to the luminous conversion portion nor contaminating the surface of the same.
At that time, the above handling portion may be constituted such that it has a form extending straightforward and is integrated with the edge portion at an approximately middle point between both ends thereof. The handling portion may take the form of an approximately rectangular parallelepiped, the edge portion may take the form of an approximately circular arc, and the circular arc form may extend from the formation plane side of the luminous flux conversion portion to the opposite plane side thereof, thereby forming a projection portion of the semi-cylindrical type.
It is preferable for the handling portion to have a flat plane. With this flat plane, the handling portion can be easily sucked in and held with ease by means of the suction means. At that time, the handling portion may be constituted such that it has a form extending straightforward and at the same time while the flat plane is a plane existing along the direction toward which the handling portion extends, and is approximately vertical to the surface of the luminous flux conversion portion.
It is preferable that the handling portion is asymmetrically formed with respect to a virtual plane which includes the optical axis of the luminous flux conversion portion and goes across the handling portion, in order to identify either one of both surfaces of the optical substrate, or that the handling portion includes a guide mark for identifying either one of both surfaces of the optical substrate.
If the luminous flux conversion portion is formed on either one face of the optical substrate, by making the handling portion asymmetric or by putting the guide mark on the handling portion, it is discriminated with ease on which one face the luminous flux is. On one hand, even if luminous flux conversion portions having different optical characteristics are respectively formed on the both faces of the optical substrate, it is also discriminated with ease which luminous flux conversion portion is on which face.
The optical member is an optical member to be mounted on a supporting substrate and is preferably with a positioning mark formed on the plane which is approximately vertical to the surface of the luminous flux conversion portion in the handling portion and approaches the supporting substrate at the time of mounting the optical member.
According to such a constitution as described above, as the positioning of the optical element can be carried out by using the positioning mark, the optical element can be packaged with high accuracy and with ease as well, irrespective of the external form thereof.
At that time, the positioning mark may take the form of a groove, of which the cross section has one of the shapes of an approximately V-shape, an approximately trapezoid shape, an approximately semicircular shape, an approximately rectangle shape, and an approximately square shape.
It is preferable that the positioning mark is asymmetrically formed with respect to a virtual plane which includes the optical axis of the luminous flux conversion portion and goes across the handling portion, in order to identify either one of both surfaces of the optical substrate. According to the constitution like this, if the luminous flux conversion portion is formed on either one face of the optical substrate, by making the handling portion asymmetric, it is discriminated with ease with the help of the mark on which one face the luminous flux is. On one hand, even if luminous flux conversion portions having different optical characteristics are respectively formed on the both faces of the optical substrate, it is discriminated also with ease which luminous flux conversion portion is on which face.
The optical member is an optical member which is arranged on a groove portion as formed on the supporting substrate for use in arrangement of optical members, such that it opposes to the end face of an optical fiber placed on the groove portion and achieves an optical coupling to the optical fiber. The edge portion has a circular arc form, which extends from the luminous flux conversion portion formation plane side to the opposite plane side thereof, and the outer diameter of the circular arc shape is preferably made equal to that of the optical fiber. According to the constitution like this, the both optical axes of the optical fiber arranged on the groove portion for use in the member arrangement and the optical member can be coincided with each other relatively with high accuracy and with ease as well.
According to the other aspect of the invention, there is provided an optical member including a plurality of luminous flux conversion portions formed on the surface of an optical substrate; edge portions formed along a part of respective circumferences of a plurality of the luminous flux conversion portions; and a handling/supporting portion which is provided on the side of the other part of respective circumferences of a plurality of the luminous flux conversion portions and is extended in a plane approximately in parallel with the surface of the luminous flux conversion portions, and connects and supports a plurality of the luminous flux conversion portions together.
At that time, a plurality of luminous conversion portions as described above may take the form of an array and the handling/supporting may be constituted such that it takes the form extending along the direction toward which the array extends.
According to another aspect of the invention, there is provided an optical member manufactured by a manufacturing method including:
the first step of forming a plurality of luminous flux conversion portions in the form of an array on an optical substrate; and
the second step of forming an edge portion along a part of the circumference of each of the luminous flux conversion portions, and a handling supporting portion which is provided on the side of the other part of the circumference of each of the luminous flux conversion portions and is extended to connect and support at least two of the luminous flux conversion portions together along the array of the luminous flux conversion portions, whereby there is obtained an optical element aggregation provided with a plurality of the luminous flux conversion portions, edge portions corresponding to a plurality of the luminous flux conversion portions, and the handling/supporting portion connecting and supporting these together, the optical member including:
at least one of the luminous flux conversion portions;
an edge portion formed along a part of the luminous flux conversion portion; and
a handling/supporting portion connecting and supporting these together.
According to another aspect of the invention, there is provided an optical member manufactured by a manufacturing method including:
the first step of forming a plurality of luminous flux conversion portions in the form of an array on an optical substrate;
the second step of forming an edge portion along a part of the circumference of each of the luminous flux conversion portions, and a handling/supporting portion which is provided on the side of the other part of the circumference of each of the luminous flux conversion portions and is extended to connect and support at least two of the luminous flux conversion portions together along the array of the luminous flux conversion portions, whereby there is obtained an optical element aggregation provided with a plurality of the luminous flux conversion portions, edge portions corresponding to a plurality of the luminous flux conversion portions, and the handling/supporting portion connecting and supporting these together; and
the third step of cutting the handling/supporting portion at a predetermined portion, thereby producing a plurality of individually separated optical elements of which each includes at least one of the luminous flux conversion portions, the optical member including:
at least one of the luminous flux conversion portions;
an edge portion formed along a part of the luminous flux conversion portion; and
a handling portion which is formed by cutting the handling/supporting portion and is extended on the side of the other part of the circumstance of the luminous flux conversion portion.
According to another aspect of the invention, an optical member manufactured by a manufacturing method including:
the first step of forming a plurality of luminous flux conversion portions in the form of an array on an optical substrate;
the second step of forming an edge portion along a part of the circumference of each luminous flux conversion portions, a handling/supporting portion which is provided on the side of the other part of the circumference of each of the luminous flux conversion portions and is extended to connect and support at least two luminous flux conversion portions together along the array of the luminous conversion portions, and a nick in at least one predetermined position corresponding to the interval between two of the luminous flux conversion portions in the handling/supporting portion, whereby there is obtained an optical element aggregation provided with a plurality of the luminous flux conversion portions, edge portions corresponding to a plurality of the luminous flux conversion portions, and the handling/supporting portion connecting and supporting these together; and
the third step of cutting the handling/supporting portion at a nick position, thereby producing a plurality of individually separated optical elements of which each includes at least one of the luminous flux conversion portions, the optical member including:
at least one of the luminous flux conversion portions;
an edge portion formed along a part of the luminous flux conversion portion; and
a handling portion which is formed by cutting the handling/supporting portion and is extended on the side of the other part of the circumstance of the luminous flux conversion portion, the handling portion having a part of the nick and a cut face on the side face thereof.
In all the optical members as described above, the optical substrate may be a silicon crystalline substrate, the luminous flux conversion portion may be made up of diffractive optical elements, and the luminous flux conversion portion may be a lens.
According to another aspect of the invention, there is provided a method for manufacturing an optical member including the first step of forming a plurality of luminous flux conversion portions in the form of an array on an optical substrate; and the second step of forming an edge portion along a part of the circumference of each of the luminous flux conversion portions, and a handling/supporting portion which is provided on the side of the other part of the circumference of each of the luminous flux conversion portions and is extended to connect and support at least two of the luminous flux conversion portions together along the array of the luminous flux conversion portions, whereby there is obtained an optical element aggregation provided with a plurality of the luminous flux conversion portions, edge portions corresponding to a plurality of the luminous flux conversion portions, and the handling/supporting portion connecting and supporting these together.
According to the constitution like this, a plurality of luminous flux conversion portions can be integrated into one body by connecting and supporting them by the handling/supporting portion, thus enabling them to be handled in a lump. With this, the optical member can be collected and handled with ease and also, it can be easily moved to the thin film formation process for forming coating films, for instance an anti-reflection film, a filter film, and so forth.
According to another aspect of the invention, there is provided a method for manufacturing an optical member including the first step of forming a plurality of luminous flux conversion portions in the form of an array on the surface of an upper silicon layer surface of a optical substrate made up of a lower silicon layer, an upper silicon layer and a middle layer intervening therebetween; the second step of forming a edge portion along a part of the circumference of each of the luminous flux conversion portions by etching the upper silicon layer and at the same time, forming a handling/supporting portion by etching the upper silicon layer, the handling/supporting portion being provided on the side of other part of the circumference of each of the luminous flux conversion portions and extended to connect and support at least two of the luminous flux conversion portions together along the array of the luminous flux conversion portions, thereby obtaining an optical element aggregation provide with a plurality of the luminous flux conversion portions, edge portions corresponding to the luminous flux conversion portions, and the handling/supporting portion for connecting and supporting these altogether; and the third step of removing the middle layer, thereby separating the lower silicon layer from the optical element aggregation as obtained by the second step.
According to the constitution like this, a plurality of luminous flux conversion portions can be integrated into one body by connecting and supporting them by the handling/supporting portion, thus enabling them to be handled in a lump. With this, the optical member can be collected and handled with ease and also, it can be easily moved to the thin film formation process for forming coating films, for instance an anti-reflection film, a filter film, and so forth. Furthermore, when etching the silicon layer, for instance, the photolithographic etching method as used in the semiconductor manufacturing technique can be adopted and a lot of optical members can be formed in a lump with high accuracy.
In the method for manufacturing the optical member as described above, it may be possible to two-dimensionally arrange a plurality of luminous flux conversion portions in a plane approximately in parallel with the surface of the luminous flux conversion portions in the first step, and in the second step, to form a plurality of optical element aggregations and at the same time, a connecting portion for connecting at least each one side end of the handling/supporting potions of a plurality of the above optical element aggregations with one another, thereby obtaining an optical element aggregation group. Or again, it may be possible to two-dimensionally arrange a plurality of luminous flux conversion portions in a plane approximately in parallel with the surface of the luminous flux conversion portions in the first step, and in the second step, to form a plurality of optical element aggregations and at the same time, a connecting portion for connecting both ends of the handling/supporting potions of a plurality of the above optical element aggregations with one another, thereby obtaining an optical element aggregation group.
According to the constitution as described above, a plurality of luminous flux conversion portions are two-dimensionally arranged and an optical element aggregation group consisting of a plurality of optical element aggregations connected with each other is formed, so that these plural optical element aggregations can be handled in a lump, thus handling of them being made much easier.
The above method for manufacturing the optical member may be further provided with a step of forming a frame in at least a part of the circumferential edge portion of the optical substrate, the frame being connected with the optical element aggregation group through the connecting portion. According the constitution like this, the optical element aggregation group is firmly supported by the frame associated therewith, so that it becomes possible to handle it by means of a suitable automatic machine.
The above method for manufacturing the optical member may be further provided with a step of cutting the handling/supporting portion at a predetermined position, thereby producing individually separated optical elements of which each has at least one luminous flux conversion portion. According to the constitution like this, the individually separated optical elements can be produced from the optical element aggregation or the optical element aggregation group by a desired number of them.
The above second step may further include the steps of providing a nick in at least one predetermined position corresponding to the interval between the luminous flux conversion portions in the handling/supporting portion at the time of forming the handling/supporting portion in the second step and cutting the handling/supporting portion at the position of the nick, thereby producing individually separated optical elements of which each has at least one luminous flux conversion portion. According to the constitution like this, the work for separating the optical element aggregation or the optical element aggregation group into individually separated ones is facilitated.
According to another aspect of the invention, there is provided a method for mounting an optical member having a luminous flux conversion portion on a supporting substrate, including the steps of forming the first mark for positioning on the plane of the optical member which is approximately vertical to the surface of the luminous flux conversion portion and approaches the supporting substrate at the time of mounting the optical member; and forming the second mark for positioning on the supporting substrate, whereby the optical member is suitably mounted on the supporting substrate with the help of the first mark of the optical member and the second mark on the supporting substrate as well.
According to the constitution like this, the optical member can be mounted with high accuracy and ease as well by using the first positioning mark for the optical member and the second positioning mark for a position on the supporting substrate as reference marks. At this time, the first positioning mark for the optical member may take the form of a groove while the second positioning mark for a position on the supporting substrate may take the form of a recess portion.
In the above method, the optical member may include a luminous flux conversion portion formed on the surface of an optical substrate, an edge portion formed along a part of the circumference of the luminous flux conversion portion, and a handling portion which is provided on the side of the other part of the circumference of the luminous flux conversion portion in a plane approximately in parallel with the surface of the luminous flux conversion portion, and is extended with a width wider than the luminous flux portion, wherein the above positioning groove may be provided on the handling portion.
According to another aspect, there is provided a module including a supporting substrate on the surface of which a groove portion for use in arranging members thereon is formed; an optical fiber arranged on the groove portion; and an optical member arranged on said groove portion such that it opposes to the end face of the optical fiber and achieves an optical coupling thereto, wherein the optical member including a luminous flux conversion portion formed on the surface of an optical substrate; an edge portion formed along a part of the circumference of the luminous flux conversion portion; and a handling portion which is provided on the side of the other part of the circumference of the luminous flux conversion portion in a plane approximately in parallel with the surface of the luminous flux conversion portion, and is extended with a width wider than the luminous flux portion.
At that time, the edge portion may have a circular arc form, which extends from the luminous flux conversion portion formation plane side to the opposite plane side thereof, and the outer diameter of the circular arc shape may be made equal to that of the optical fiber.
In the module as described above, the supporting substrate is further provided with a positioning mark, the optical member is further provided with a positioning groove as formed in a plane which is approximately vertical to the surface of the luminous flux conversion portion in the handling portion and approaches the supporting substrate at the time of mounting optical members, and the optical member is arranged in part on the groove portion formed on the supporting substrate with the help of the positioning groove of the optical member and the positioning mark on the supporting substrate.
According to the constitution like this, the optical member is arranged in part on the groove portion by carrying out the positioning using the groove of the optical member and the mark on the supporting substrate, so that a module packaged with high accuracy can be provided.
At that time, the above mark may be a recess portion which intersects the groove portion at right angles.
According to another aspect of the invention, there is provided a module including a supporting substrate on the surface of which a plurality of groove portions for use in arranging members thereon is formed; a plurality of optical fibers arranged on each of the groove portion; and optical members arranged on each of said groove portions such that each of them opposes to each end face of each of the optical fibers and achieves an optical coupling thereto, wherein the optical member includes a plurality of luminous flux conversion portions formed on the surface of an optical substrate; edge portions formed along a part of respective circumference of the luminous flux conversion portion; and a handling/supporting portion which is provided on the side of the other part of respective circumference of a plurality of the luminous flux conversion portions in a plane approximately in parallel with the surface of the luminous flux conversion portion, and is extended to connect and support a plurality of the luminous flux conversion portions together.
At that time, each end face of a plurality of the optical fibers may be arranged to oppose to each of a plurality of luminous flux conversion portions of the optical member, and each of the edge portions may have a circular arc form, which extends from the luminous flux conversion portion formation plane side to the opposite plane side thereof, and the outer diameter of the circular arc shape may be made equal to that of each of the optical fibers opposing to each of the luminous flux conversion portions corresponding to each of the edge portion.
In the module as described above, the supporting substrate may be further provided with a positioning mark, the optical member may be further provided with a positioning groove as formed in a plane which is approximately vertical to the surface of the luminous flux conversion portion in the handling/supporting portion and approaches the supporting substrate at the time of mounting optical members, and the optical member is arranged in part on the groove portion formed on the supporting substrate with the help of the positioning groove of the optical member and the positioning mark on the supporting substrate.
At that time, the above mark may be a recess portion which intersects the groove portion at right angles.